This invention relates generally to vibratory compactors and more particularly to improved construction of such compactors.
Vibratory compactors are generally well known and include self-contained units such as that taught by U.S. Pat. No. 3,782,845 issued to Briggs, et al on Jan. 1, 1974, and boom carried hydraulically powered units such as that taught by U.S. Pat. No. 3,917,426 issued to Wohlwend, et al on Nov. 4, 1975. The devices taught by these two patents and numerous other patents cited therein all employ a rotating eccentrically weighted shaft for vibrating a base plate which rides on loose earth, gravel, etc., which is to be compacted. The various known devices differ in the type of motor used to drive the eccentric weighted shaft and in the basic construction of the devices.
Reliability of mechanical devices tends to be improved by reduction in the number of component parts that go to make up the whole device. This reduction in parts typically also reduces the overall cost of the device. But with vibratory compactors, it is, of course, necessary that the device be extremely rugged to withstand its own internally generated vibrations and to withstand the rough treatment which is incident to the construction work in which the devices are used.
The above referenced Wohlwend patent illustrates a concern for ruggedness and a somewhat simplified construction when compared to earlier devices. That patent used two tubular members to hold U-shaped side members in a spaced apart parallel condition. It can be seen that this requires that both tubular members be cut to precisely the same length, that the cut ends be at a precise right angle to the tube axis and that circular welds be made. In addition, the construction of Wohlwend employs four connector plates attached to the four corners of the baseplate for connecting shear springs to the side plates. The vibration motor is separately mounted on the compaction plate. Thus it is seen that the complete unit comprises a fairly large number of separate parts.